It is well known that a conventional electromagnetic valve in which a fluid is disposed around an opening portion of a passage hole at a valve seat, a valve element displaces according to a fluid force and a magnetic attractive force, and a passage area between the valve element and the valve seat varies. In this case, the valve seat is taper-shaped. According to JP-2011-99563A, a rod is taper-shaped. Since the valve element slides along the valve seat and displaces, an oscillation of the valve element is restricted, and a control safety is ensured.
However, since the valve element slides on a surface of the valve seat and displaces, a frictional resistance is generated between the valve element and the valve seat when the valve element is closed. Therefore, a required magnetic attractive force is increased, and a size of the electromagnetic valve is also increased. Further, since it is necessary to process the rod to a taper shape, man-hours are increased.